package main

import "fmt"

type ParamsError struct {
}
func (*ParamsError) Error () {
}

type User struct {
	Name string
	Age int
}
func (u *User) NewUser(name string, age int) (User, error) {
	if age < 1 || age > 99 {
		return nil, ParamsError{}
	} else {
		return User{Name: name, Age: age}, nil
	}
}

func main() {
}
